Association of GPR120 and NGF with perineural invasion in cholangiocarcinoma: Clinical and experimental insights.

622 Background: Cholangiocarcinoma (CCA) is a highly malignant biliary tumor characterized by frequent perineural invasion (PNI), which is associated with a poor prognosis; however, the underlying mechanisms remain unclear. G-protein-coupled receptor 120 (GPR120) has been implicated in the development of various tumors, while nerve growth factor (NGF) has a strong correlation with PNI. This study aims to elucidate the role of GPR120 in the production of NGF and to investigate the mechanisms by which PNI is induced in CCA. Methods: We conducted a retrospective review of medical records for 386 patients with cholangiocarcinoma (CCA), including both extrahepatic (ECC) and intrahepatic (ICC) types, who underwent curative resection at the Department of General Surgery, First Affiliated Hospital of Soochow University, between January 2015 and December 2021. NGF and GPR120 expression were assessed in 60 paraffin-embedded archived CCA tissue samples via immunohistochemical staining (IHC), with an additional 60 normal bile duct samples serving as controls. All tissues were sourced from the aforementioned 386 patients, none of whom received preoperative treatment. Tumors were staged according to AJCC classification. Western blot analysis was employed to evaluate NGF and GPR120 expression in CCA cell lines (QBC 939, RBE, HUCCT-1, and HCCC-9810). To assess the invasion and migration capabilities of CCA cell lines, QBC 939 and HCCC-9810 were treated with TUG-891 (a GPR120 agonist) and AH7614 (a GPR120 inhibitor). Results: Both GPR120 and NGF were found to be upregulated in CCA tissues, correlating with aggressive clinicopathological features. IHC staining revealed cytoplasmic localization of GPR120 and NGF, with significantly higher expression in cancerous tissues compared to adjacent noncancerous samples. Among the 386 patients, PNI was observed in 339 (87.8%). PNI correlated with tumor diameter, CA 19-9 levels, TNM stage, preoperative bilirubin levels, tumor differentiation, and preoperative drainage. Notably, GPR120 expression increased in poorly differentiated tumors and advanced clinical stages, indicating a clinical association with CCA progression. In vitro studies demonstrated that GPR120 promoted invasion and migration in the QBC 939 and HCCC-9810 cell lines. Western blot analysis confirmed elevated GPR120 levels in these lines, which also exhibited higher NGF expression. The GPR120 inhibitor AH7614 significantly reduced invasion in QBC 939 and HCCC-9810 cells, while the GPR120 agonist TUG-891 showed no effect on any of the CCA cell lines tested. Conclusions: GPR120 and NGF are implicated in perineural invasion (PNI) in CCA, with a notable correlation between GPR120 and NGF in the context of PNI occurrence.